human neural Visual pathway easy.pptx 1.pptx

Light enters the eye through the cornea and pupil, then passes through the lens.
The lens focuses light onto the retina, where specialized cells called photoreceptors (rods and cones) detect light.
Photoreceptors convert light into electrical signals.
These signals travel along the optic nerve to the optic chiasm, where some fibers cross over to the opposite side.
The optic tracts carry the signals to the lateral geniculate bodies in the thalamus.
From there, the optic radiations project to the visual cortex in the occipital lobe, where visual processing occurs.

1. The Visual Pathway

2. Parts of the Eye

3. PARTS OF THE EYE Aqueous humor - clear watery fluid found in the anterior chamber of the eye; maintains pressure and nourishes the cornea and lens Vitreous humor - clear, jelly-like fluid found in the back portion of the eye: maintains shape of the eye and attaches to the retina Blind spot - small area of the retina where the optic nerve leaves the eye: any image falling here will not be seen Ciliary muscles - involuntary muscles that change the lens shape to allow focusing images of objects at different distances Cornea - transparent tissue covering the front of the eye: does not have blood vessels; does have nerves Cones -photoreceptors responsive to color and in bright conditions; used for fine detail Rods - photoreceptors responsive in low light conditions; not useful for fine detail

4. Parts of the eye - continued Fovea - central part of the macula that provides sharpest vision; contains only cones Iris - circular band of muscles that controls the size of the pupil. The pigmentation of the iris gives "color" to the eye. Blue eyes have the least amount of pigment; brown eyes have the most Lens - transparent tissue that bends light passing through the eye: to focus light, the lens can change shape Macula - small central area of the retina that provides vision for fine work and reading Optic nerve - bundle of over one million axons from ganglion cells that carry visual signals from the eye to the brain Pupil - hole in the center of the eye where light passes through Choroid - Thin tissue layer containing blood vessels, sandwiched between the sclera and retina; also, because of the high melanocytes content, the choroid acts as a light-absorbing layer. Retina - layer of tissue on the back portion of the eye that contains cells responsive to light (photoreceptors) Sclera - tough, white outer covering of the eyeball; extraocular muscles attach here to move the eye

5. Visual Pathway Imagine that the colored bar (half red, half blue) is in front of your eyes. The red part of the bar will project to the nasal part of your left retina and the temporal (lateral) part of your right retina. The blue part of the bar will project to the nasal part of your right retina and the temportal (lateral) part of your left retina.

6. Visual pathway Like many pathways in the nervous system, right and left visual information cross to the other side of the brain. This occurs in the optic chiasm. After the optic chiasm, information about the right visual field (blue) is on the left side of the brain, and information about the left visual field (red) in on the right side. The pathways stay this way and all the way up to the visual cortex.

7. Visual pathway Follow the blue and red lines from the eyes to see the flow of information. From the retina, the first synapse is in the lateral geniculate nucleus of the thalamus. The next synapse is made in primary visual cortex in the occiptal lobe.

8. The Visual Pathway